Fracture resistant brush head

ABSTRACT

This application relates to electric toothbrushes and in particular to a brush section for an electric toothbrush. The brush section may include static contact elements and movable contact elements to perform a cleaning operation. A head portion of the brush section is resistant to fractures or other material damage which might result from impacts, such as for example caused by dropping the toothbrush. It is structured to transmit forces from the impact away from an interior region of the head portion, to pass through the side portions of the head portion.

FIELD OF THE INVENTION

This application relates to electric toothbrushes and in particular to abrush section for an electric toothbrush.

BACKGROUND OF THE INVENTION

An electric toothbrush may incorporate a brush section that couples to ahandle section. Mechanical linkages may connect one or more movableportions in the brush section to an electric drive disposed within aninterior of the handle section. The electric drive may impart a rotary,oscillating or combined rotary oscillating motion to the movableportions so that they move in a rotary or oscillating manner. Themovement of the movable portions provide a desired cleaning action.

Electric toothbrushes are often larger in size than non-electrictoothbrushes, due to the presence of an electric motor, batteries,various mechanical linkages, electrically-driven head portions, andother components. Electric toothbrushes also often weigh more thannon-electric toothbrushes, again due to the presence of those variouscomponents. In order to minimize the physical size and weight of anelectric toothbrush, many of the individual components can bemanufactured to be as small and light as practical. One of the factorslimiting the use of small and light components in an electricaltoothbrush, however, is durability. For example, it is desirable for atoothbrush to meet certain “drop test” requirements. In this context, adrop test specifies one or more laboratory conditions which aretypically meant to emulate what would occur if a user were to drop thetoothbrush. Such conditions include, for example, the height of a drop,the orientation of the toothbrush when it is dropped, the material andconditions of the surface impacted by the toothbrush to stop its fall,and the like. The toothbrush passes the drop test if, after beingdropped under the specified conditions, it is not fractured or otherwisematerially damaged. Thus, the choice of materials and degree ofminimization to reduce the physical size and weight of a toothbrush islimited by durability requirements, such as drop test requirements.

The present application sets forth an electric toothbrush design whichadvantageously increases the resistance of the brush head to fracturesor other material damage which might otherwise result from impacts, suchas for example caused by dropping the toothbrush.

SUMMARY OF THE INVENTION

In one embodiment, a brush section for an electrical toothbrush housingan electric drive, the brush section having a head portion includes aframe including a first plurality of contact elements supported withinthe frame; a movable contact element holder including a second pluralityof contact elements supported within the movable contact element holder;and an extension portion of the movable contact element holder arrangedat a tip end of the head portion, with a gap disposed between theextension portion and the frame. The movable contact element holderbeing structured to receive a cleaning motion from the electric drive tohave at least one freedom of motion relative to the first plurality ofcontact elements. And, at least a first portion of the gap in a sideperiphery region of the head portion is smaller in width than a secondportion of the gap in an interior region of the toothbrush head.

In another embodiment, a brush section for an electrical toothbrushhousing an electric drive, the brush section having a head portionincludes a frame including a first plurality of contact elementssupported within the frame; a movable contact element holder including asecond plurality of contact elements supported within the movablecontact element holder; an extension portion of the movable contactelement holder arranged at a tip end of the head portion; and means fordistributing an impact force away from an interior region of the headportion. The movable contact element holder being structured to receivea cleaning motion from the electric drive to have at least one freedomof motion relative to the first plurality of contact elements.

In another embodiment, a brush section for an electrical toothbrushhousing an electric drive, the brush section having a head portionincludes a frame including a first plurality of contact elementssupported within the frame; a movable contact element holder including asecond plurality of contact elements supported within the movablecontact element holder; and an extension portion of the movable contactelement holder arranged at a tip end of the head portion, with a gapdisposed between the extension portion and the frame. The movablecontact element holder being structured to receive a cleaning motionfrom the electric drive. And, the gap is configured such that the brushhead portion is able to absorb at least about 1.3 Newtons of energyapplied via a force D without fracture.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter that is regarded as thepresent invention, it is believed that the invention will be more fullyunderstood from the following description taken in conjunction with theaccompanying drawings. None of the drawings is necessarily to scale.

FIG. 1 is a perspective view of an electric toothbrush.

FIG. 2A is an exploded perspective view of the brush section of thetoothbrush shown in FIG. 1.

FIG. 2B is a perspective view of the brush section illustrated in FIG.2A, in an assembled condition.

FIG. 2C is a back view of the head portion of the brush sectionillustrated in FIGS. 2A and 2B.

FIG. 2D is a side view of the head portion of the brush sectionillustrated in FIGS. 2A to 2C.

FIG. 2E is a top view of the head portion of the brush sectionillustrated in FIGS. 2A to 2D, and employing a different bristleconfiguration at the tip of the head.

FIG. 3 is a partial top view of the head portion of the brush sectionillustrated in FIGS. 2A to 2E, focusing on the bumper.

FIG. 4 is a partial perspective view of the head portion of the brushsection illustrated in FIGS. 2A to 2E, focusing on the bumper.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates an exemplary electric toothbrush 10. The electrictoothbrush 10 includes a brush section 200 and a handle section 12. Thebrush section 200 is more particularly shown in FIGS. 2A to 2E, and isdiscussed in more detail below. The handle section 12 includes aninterior cavity (not shown) which typically contains an electric drivesuch as a motor, batteries, mechanical linkages for connecting theelectric drive to further mechanical linkages in the brush section 200,electronic components for controlling the electrical operation of thetoothbrush 10, and the like. In many different embodiments, one or moreof those interior components may be omitted, or replaced with othercomponents. For example, a corded electrical power supply can supplantthe need for batteries. A switch 14 may be used to turn the electrictoothbrush 10 on and off, or otherwise to control operation of theelectric toothbrush 10.

The electric drive in the handle section 12 imparts a motion to themechanical linkages in the handle section 12. It may, for example,impart a rotary, oscillating, or rotary and oscillating motion to themechanical linkages. The mechanical linkages in the handle section 12are in turn coupled to additional mechanical linkages in the brushsection 200, via a coupling member or the like. A suitable motor andmechanical linkage transmission system is disclosed for example in U.S.Patent Application Publication No. 2008/0307591 to Farrell et al., whichis hereby incorporated by reference in its entirety. Movement of thecombined mechanical linkages imparts a desired motion to a brush headportion 220 of the brush section 200 such that the brush head portion220, or any component thereof, is caused to have a desired cleaningmotion. Many different kinds of cleaning motions, including rotary,oscillating, vertical and/or horizontal sweeping and the like, may beused. Generally, as used herein, cleaning motion describes any desiredor effective movement of the bristles relative to other components inthe toothbrush 10 to affect cleaning. Handle sections 12 and mechanicallinkages are well known to the skilled artisan. The brush section 200may be configured for use with such existing handle sections or may beconfigured with new handle section types, as the case may be.

The brush section 200, shown in more detail by FIGS. 2A to 2E, 3 and 4,may be push-fitted onto the handle section 12. The brush section 200includes a mounting tube 212 extending along a longitudinal axis 214.The longitudinal axis 214 may coincide with a longitudinal section of adrive shaft member of the mechanical linkages. At a handle end 216, themounting tube 212 may include a profile ring having an inside contourcomplementary with an outside contour of the handle section 12. In thismanner, the brush section 200 can be push-fitted onto the handle section12 in a manner preventing relative rotation of the brush section 200with respect to the handle section 12. A tab/slot, key/spline or othersimilar structure may be included in the corresponding contour surfacesto facilitate alignment of the brush section 200 with the handle section12 and to further prevent relative rotation between the two.Alternatively, the mounting tube 212 may be integrally formed with thehandle section 12.

The illustrated brush head portion 220 has an elliptical shape, althoughit may alternatively have a generally rectangular, oblong, or othersuitable shape. Generally, the brush head portion 220 may have alength-to-width aspect ratio greater than one, although such anarrangement is not required.

In some embodiments, the brush head portion 220 includes a frame 222which supports a first plurality of contact elements 224 that aremounted to the frame 222 so as to be fixed, i.e., they are staticrelative to the frame 222. Any suitable method of mounting the firstplurality of contact elements 224 to the frame 222 may be used. Forexample, where the contact elements 224 comprise a plurality ofbristles, methods such as hot tufting, gluing, stapling, and the like,may be utilized. As another example, where the contact elements 224comprise a plurality of elastomeric elements, methods such as gluing,snap-fitting, welding, molding, etc. may be utilized.

Supported within the frame 222, such as by a snap fit for example, is amovable contact element support or movable contact element holder 226supporting a second plurality of contact elements 228. The secondplurality of contact elements 228 may be mounted to the movable contactelement holder 226 using any suitable method, as described above withregard to the first plurality of contact elements 224. The movablecontact element holder 226 may be supported within the frame 222 suchthat it is able to rotate about the longitudinal axis 214 in response toa suitable driving input from the handle section 12, as transferred bythe mechanical linkages. In this way the second plurality of contactelements 228 are movable in a cleaning motion relative to the firstplurality of contact elements 224.

The first plurality of contact elements 224 may be arranged in rowstransverse relative to the axis 214. Similarly, the second plurality ofcontact elements 228 may be arranged in rows transverse relative to theaxis 214. In some embodiments, the transverse rows may alternate betweenrows of first plurality of contact elements 224 and rows of secondplurality of contact elements 228. In some embodiments, multiple rows ofthe first plurality of contact elements may be separated by a row ormultiple rows of the second plurality of contact elements 228 and viceversa or the rows may be interleaved or arranged in virtually anymanner. The rows of the first plurality of contact elements 224 mayadvantageously be longer in length than the rows of the second pluralityof contact elements 228.

The movable contact element holder 226 may include an extension portion244 supporting a third plurality of contact elements 246. FIG. 2Eillustrates a slightly different configuration of contact elements 246′disposed within the extension portion 244 from the other figures herein.The extension portion 244 may be supported to permit at least onefreedom of motion relative to the frame 222. For example, the extensionportion 244 may be supported to rotate relative to the frame 222. Inthis manner, the third plurality of contact elements 246 may move in acleaning motion relative to the first plurality of contact elements 224and/or the second plurality of contact elements 228. For example, theextension portion 244 may couple to the movable bristle holder 226 suchthat the third plurality of contact elements 246 moves in a similarmanner as the second plurality of contact elements 228.

In the embodiment of FIGS. 2A to 2E, the coupling between the extensionportion 244 and the movable contact element holder 226 is direct suchthat the extension portion 244 moves with the movable contact elementholder 226. However, in some embodiments, the extension portion 244 mayinstead couple to the mechanical linkages in the brush section 200directly, and/or to the movable contact element holder 226 or otherwisesuch that the extension portion 244 has a cleaning motion that isseparate from a cleaning motion of the movable contact element holder226 and the second plurality of contact elements 228. In otherembodiments, the frame 222 may comprise the extension portion 244 tohold the third plurality of contact elements 246. In such embodiments,the third plurality of contact elements 246 may be stationary withrespect to the frame 222.

In the embodiment shown in FIGS. 2A to 2E, the movable contact elementholder 226 may oscillate about the axis 214 thereby causing the secondplurality of contact elements 228 and/or the third plurality of contactelements 246 to similarly oscillate about the axis 214. The movement ofthe movable contact element holder 226 may cause the second plurality ofcontact elements 228 and/or the third plurality of contact elements 246to oscillate back and forth angularly to provide a cleaning actionsubstantially similar to an up-down manual brushing action. The amountof angular movement as well as the speed exhibited by the movablecontact element holder 226 and the second plurality of contact elements228 and/or the third plurality of contact elements 246 can impact theefficacy of the cleaning action.

In some embodiments, the brush section 200 may comprise a transponder,and the handle section 12 may house a detector or a reading device asdescribed in U.S. Patent Application Publication Nos. 2004/0255409 and2003/0101526. The transponder can be configured to communicateinformation about the brush section 200 to the detector or readingdevice. The reading device or detector can be in signal communicationwith a controller in the handle section 12 which may be configured tocontrol the speed of the motor and/or the movement of the mechanicallinkages in the handle section 12. The basic architecture of acontroller, reading device, detector, and/or transponder is generallyknown.

The speed of the motor as well as the angle of oscillatory shaftdisplacement can be controlled in any suitable manner. For example, onemeans of modifying the speed of the motor is to increase or decrease thevoltage to the motor. Typically, an increase in voltage will increasethe speed of the motor while a decrease in voltage will decrease thespeed of the motor. Such mechanisms for modifying the voltage deliveredto motors are well known. As another example, the speed of the motor maybe modified via a transmission system.

The first plurality of contact elements 224, the second plurality ofcontact elements 228, and/or the third plurality of contact elements 246of the present invention may comprise a wide variety of materials andmay have a number of different configurations. Any suitable materialand/or any suitable configuration may be utilized. For example, in someembodiments, the first plurality of contact elements 224, the secondplurality of contact elements 228, and/or the third plurality of contactelements 246, may comprise tufts. The tufts may comprise a plurality ofindividual filaments which are securely attached to a cleaning elementcarrier. Such filaments may be polymeric and may include polyamide orpolyester. The longitudinal and cross sectional dimensions of thefilaments of the invention and the profile of the filament ends canvary. Additionally, the stiffness, resiliency and shape of the filamentend can vary. Some examples of suitable dimensions include a lengthbetween about 3 centimeters to about 6 centimeters, or any individualnumber within the range. Additionally, the filaments may include asubstantially uniform cross-sectional dimension of between about 100 toabout 350 microns, or any individual number within the range. The tipsof the filaments may be any suitable shape, examples of which include asmooth tip, a rounded tip, and a pointed tip. In some embodiments, thefilaments may include a dye which indicates wear of the filaments asdescribed in U.S. Pat. No. 4,802,255. Other suitable examples offilaments are described in U.S. Pat. No. 6,018,840. In some embodiments,the cleaning element fields may comprise fins as described in U.S. Pat.No. 6,553,604, and U.S. Patent Application Publication Nos.2004/0177462; 2005/0235439; and 2005/0060822. In some embodiments, thecleaning element fields may comprise a combination of fins and tufts.

Additionally, at least a portion of some of the first plurality ofcontact elements 224, the second plurality of contact elements 228,and/or the third plurality of contact elements 246 may be attached to acleaning element carrier at an angle. Such orientations are described inU.S. Pat. No. 6,308,367. Also, any suitable method may be utilized toattach the first plurality of contact elements 224, the second pluralityof contact elements 226, and/or the third plurality of contact elements246 to their respective structures.

Embodiments are contemplated where the mounting tube 212 is angled withrespect to the handle section 12. In such embodiments, the mechanicallinkages between the motor and the brush head portion 220 of the presentinvention may be provided in discrete portions thereby accommodating theangle of the mounting tube 212. For example, the mechanical linkages mayinclude a drive shaft with one or more universal joints, or a driveshaft constructed from a compliant material. Some examples of suitablematerials for construction of the drive shaft include aluminum, springsteel, plastics, e.g. delrin, nylon, polypropylene, and/or combinationsthereof.

The second plurality of contact elements 228 extend through apertures270 formed in the frame 222 so that the contact elements 224 and 228form a unitary contact element field to perform a brushing operation. Inoperation, the second plurality of contact elements 228 move withrespect to the first plurality of contact elements 224, in a motion verysimilar to the motion a user would perform with a manual oral cleaningdevice such as a manual toothbrush. A drive shaft (not shown) may extendthrough the frame 222 to be supported in the extension portion 244 ofthe movable contact element holder 226. The drive shaft can be adaptedto engage a mechanical linkage in the handle section 12. The movablecontact element holder 226 is coupled to the drive shaft such thatoscillation of the drive shaft causes a like oscillation of the movablecontact element holder 226. Alternatively, the movable contact elementholder 226 may be coupled by a linkage, cam structure or the like suchthat the movable contact element holder 226 has a cleaning motionseparate from a rotating motion of the drive shaft. The movable contactelement holder 226 may be snap-fitted into the frame 222 and engagedwith the drive shaft.

As a general matter, electric toothbrush head portions such as theillustrated head portion 220 should be small enough to be inserted intoand moved around within a user's mouth. This design goal is complicatedby the need to include moving parts in the toothbrush head 220, such asthe movable portion 226, each of which must be large enough toadequately hold and retain contact elements such as the contact elements224, 228 and 246. The various toothbrush head parts also must besufficiently durable, such as for example to survive a typical drop ofthe toothbrush. If the toothbrush is dropped, the worst case outcome sofar as the head portion is concerned occurs when the tip of the headportion is the part which initially contacts the floor, sink or othersurface. In that scenario, the head portion must bear the full weight ofthe entire toothbrush, including the motor, batteries, and otherinternal components. Of course, other drop scenarios are also possible,and the head portion should be able to survive any reasonablypredictable drop without fracturing or otherwise being materiallydamaged.

The head portion 220 structure as shown in FIGS. 2A to 2E helps toprevent fracturing or other material damage resulting from impacts tothe head portion 220, especially in response to a force D acting on thetip 272 of the head portion 220. Force D, for example, may represent the“dropping force” acting on the toothbrush 10 if it were dropped so thatthe tip 272 of the head portion 220 is the first part to contact thefloor or sink, thus bearing the entire weight of the toothbrush 10. Asillustrated in FIG. 2E, such a force D is transmitted T away from theinterior region of the head portion 220, and through the two sideperipheries 274 of the toothbrush head 220 (the force transmission Tbeing labeled on only one side in the figure). This force transmissionis accomplished by the structure of the interface between the extensionportion 244 and the frame 222. More particularly, these two componentsare structured to leave a large gap 276 between them in a centralregion, and small gaps 278 between them in the side periphery regions274. In this way, when the extension portion 244 is deflected inwardlyby the force D, the first point of contact and therefore forcetransmission T occurs across the small gaps 278 in the side peripheryregions 274. The force transmission T thus travels down the sideperipheries 274, around the interior region where the contact elements224 and 228 are held, and down the tube portion 212 of the brush section210.

In some embodiments, such as the embodiment illustrated in FIGS. 2E, 3and 4, the small gaps may be formed by bumpers. Thus, the small gaps 278at the side peripheries 274 are formed in part by frame bumpers 290extending toward the extension portion 244. Although not illustrated inthe figures, the extension portion 244 may also include its own bumpers292, either alone or in combination with the frame bumpers 290. Theillustrated frame bumpers 290 are formed integrally with the material ofthe frame portion 222. Although not illustrated in the figures, one orthe other of the bumpers 290 and 292 may alternatively be formed of adifferent material. For example, the bumpers 290 and 292 made be madefrom an elastomeric material having a higher degree of resiliency thatthe material of the frame portion 222 or the extension portion 244. Inthat way the resiliency of the bumper material can absorb some of theforce transmission T, thus lessening the impact of the force on theentire toothbrush 10 as a whole. Such materials might include, forexample, a thermoplastic elastomer (TPE) or any one of several otherkinds of materials. One of ordinary skill in the art will be able todetermine an appropriate bumper material based on the desired elasticproperties, and the requirements for bonding to the frame portion 222 orthe extension portion 244 such as by injection molding.

Additional measures may be employed to help transmit the force T moreeffectively away from the interior region, to travel instead along theside peripheries 274 of the head portion 220. For example, it isadvantageous to increase the surface areas of the two surfaces whichabut each other across the small gaps 278 as the extension portion 244is deflected by the force D. This can be accomplished, for example, bymaking the interface between the extension portion 244 and the frame 222across the small gaps 278 to be substantially continuous, lacking sharpdiscontinuities during the rotation cycle of the extension portion 244.When the movable holder 226 is in its neutral state as shown for examplein FIGS. 2B and 2E, the interface between the extension portion 244 andthe frame 222 is substantially continuous. When the movable holder 226and the extension portion 244 rotate away from that neutral position,however, the interface will start to become discontinuous and thesurface contact area across the gaps 278 decreases. The degree ofdiscontinuity across the small gaps 278 will increase as the holder 226rotates further away from its neutral position. As one way to reducethis discontinuity, the angular extent of the rotation may be limited.As will be appreciated by one of ordinary skill in the art, thislimitation of rotation may be accomplished in many ways, such as byappropriately configuring the coupling between the movable holder 226and the electric drive in the handle section 12, or by appropriatelyconfiguring the fit of the holder 226 into the frame 222, or by othermeans.

For example, the rotation of the movable contact element holder 226 maybe limited so that each of the second plurality of contact elements 228remain within the vertical envelopes defined by the respective apertures270 through which the elements 228 extend, such as shown by the dottedcurve 270 a in FIG. 2E. As an alternative example, the rotation of themovable contact element holder 226 may be limited so that each of thesecond plurality of contact elements 228 remain within the verticalenvelope defined by the outer profile of the head portion 222, such asshown by the dotted curve 222 a in FIG. 2E. In yet further embodiments,the rotation may be limited so that only a lower portion of the heightof the contact elements 228 above the support structure remains withinone or the other of the envelopes 270 a, 222 a. The lower portion maybe, for example, 75 percent, 50 percent, or 25 percent of the height ofthe contact elements 228.

One of the advantages of directing the force transmission T down the twoside peripheries 274 of the head portion 220 is that it protects theinterior region of the head portion 220 between the side peripheries274. The respective interior regions of the frame 222 and the movablecontact element holder 226 house the contact elements 224 and 228. Thusthe durability of these interior regions can be weakened by bristlestaples and the like which hold the contact elements in place. Moreoverit may be desirable to pack the elements 224 and 228 in closelytogether, not only to reduce the overall size of the head 220, but alsoto form a more effective unitary cleaning surface. A close packing ofthe elements 224 and 228 may be accomplished by reducing the variouswall thicknesses of the frame 222 and contact element holder 226 in theinterior region, but that decreases the durability of these parts inthat region. Directing the force transmission T down the two sideperipheries 274 of the head portion 220 and thus away from the interiorregion permits a reduced amount of material to be used in the interiorregion of the head portion 220. This provides a smaller head portion 220without sacrificing the overall durability of the head portion 220.

Additional measures may be employed to direct the transmission force Taway from the interior region of the head portion 220. For example, thegap 280 between the frame 222 and the rear portion 282 of the movablecontact element holder 226 may be made small in comparison with the gap276/278 between the extension portion 244 and the frame 222. In thatway, upon application of a force D, a first portion of the force D isabsorbed by a bending movement of the extension portion 244 permitted bythe relatively large gap 276/278. A second portion of the force D isthen transmitted T through the movable portion 226, to be transferredacross the rear gap 280 by the rear portion 282 contacting the frame 222across the rear gap 282. A third portion of the force D can be absorbedby the extension portion 244 eventually closing the front gap 276/278 bycontacting the frame 222 across the small gap portions 278. In thisregard, the front gap 276/278 may be sufficiently larger than the reargap 280 so that the third portion of the force D is small enough not tothreaten the durability of the interior regions of the brush head 220.In that event, the front gap can take on any desired configuration, suchas for example having a substantially uniform width across its entireextent between the two side peripheries 274.

The brush head portion 220 structure can survive drop heights which arenormally encountered in a bathroom environment. Such drop heights canrange from about 10 centimeters (a typical depth of a sink from its rimto its bottom) to about 70 centimeters or about 80 centimeters (atypical distance between a sink top and the floor). A heavy handlesection 12 for the electric toothbrush 10 may weigh on the order of 185grams, which represents a potential dropping energy of about 1.3 Newtonsat a height of 70 centimeters. Thus, in one embodiment, the brush headportion 220 is able to absorb at least about 1.0 Newtons of energy, inanother embodiment at least about 1.1 Newtons of energy, in anotherembodiment at least about 1.2 Newtons of energy, and in yet anotherembodiment at least about 1.3 Newtons of energy, applied via a force Dwithout fracture or material damage to the brush head portion 220.

It will be understood and appreciated that while various aspects,features and advantages of the invention are described in connectionwith particular embodiments, the herein described aspects, features andadvantages may be implemented in any of the embodiments, and as such,the features and structures of the various embodiments may be mixed andmatched yielding a virtually limitless number of combinations. One ofskill in the art will furthermore appreciate that the herein describedaspects, features and advantages of the invention may be combined withstructures and devices known to or later discovered by the skilledartisan.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention. To the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the term in a document incorporated by reference, themeaning or definition assigned to the term in this written documentshall govern.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

The preceding text sets forth a broad description of numerous differentembodiments of the present invention. The description is to be construedas exemplary only and does not describe every possible embodiment sincedescribing every possible embodiment would be impractical, if notimpossible, and it will be understood that any feature, characteristic,component, composition, ingredient, product, step or methodologydescribed herein can be combined with or substituted for, in whole orpart, any other feature, characteristic, component, composition,ingredient product, step or methodology described herein. Numerousalternative embodiments could be implemented, using either currenttechnology or technology developed after the filing date of this patent,which would still fall within the scope of the claims.

What is claimed is:
 1. A brush section for an electrical toothbrushhousing an electric drive, the brush section having a head portioncomprising: a frame including a first plurality of contact elementssupported within the frame; a movable contact element holder including asecond plurality of contact elements supported within the movablecontact element holder, the movable contact element holder beingstructured to receive a cleaning motion from the electric drive to haveat least one freedom of motion relative to the first plurality ofcontact elements; an extension portion of the movable contact elementholder arranged at a tip end of the head portion, with a gap disposedbetween the extension portion and the frame; and a rear gap between arear portion of the movable contact element holder and the frame;wherein at least a first portion of the gap in a side periphery regionof the head portion is smaller in width than a second portion of the gapin an interior region of the toothbrush head; and wherein the rear gapis smaller in width than the first portion of the gap.
 2. The brushsection of claim 1, further comprising a third portion of the gap in anopposite side periphery region from the first portion of the gap,wherein the third portion of the gap is smaller in width than the secondportion of the gap.
 3. The brush section of claim 1, wherein aninterface between the extension portion and the frame across the firstportion of the gap is substantially continuous when the movable contactelement holder is in a neutral position.
 4. The brush section of claim3, wherein the frame further comprises apertures through which thesecond plurality of contact elements extend, and movement of the movablecontact element holder is limited so that at least a lower seventy-fivepercent of the height of the second plurality of contact elementsremains within vertical envelopes defined by the apertures.
 5. A brushsection for an electrical toothbrush housing an electric drive, thebrush section having a head portion comprising: a frame including afirst plurality of contact elements supported within the frame; amovable contact element holder including a second plurality of contactelements supported within the movable contact element holder, themovable contact element holder being structured to receive a cleaningmotion from the electric drive to have at least one freedom of motionrelative to the first plurality of contact elements; an extensionportion of the movable contact element holder arranged at a tip end ofthe head portion; and means for distributing an impact force away froman interior region of the head portion; wherein the frame furtherincludes apertures through which the movable contact elements extend,and movement of the movable contact element holder is limited so that atleast a lower seventy-five percent of the height of the second pluralityof contact elements remains within vertical envelopes defined by theapertures.
 6. The brush section of claim 5, wherein the distributionmeans further distributes the impact force along a side periphery of thehead portion; wherein the distribution means comprises a gap disposedbetween the extension portion and the frame, such that at least a firstportion of the gap in a side periphery region of the toothbrush head issmaller in width than a second portion of the gap in an interior regionof the toothbrush head.
 7. The brush section of claim 5, wherein atleast one bumper is disposed on at least one of the frame and theextension portion, facing toward the gap.
 8. The brush section of claim7, wherein the bumper is composed of a first material, the frame orextension portion on which the bumper is disposed is composed of asecond material, and the first material is more resilient than thesecond material.